Offshore cocktail party that no one keeps an eye on

Are Sydney's ocean outfalls safe? No one can answer that, write Anne Davies and Stephanie Peatling.

Following the conclusion of the Environment Protection Authority's $21 million monitoring program in 1993, there has been only routine monitoring of the ocean sewage outfalls despite concerns about a chemical cocktail in the system.

Sydney Water is required to monitor the toxicity of effluent, including quantities of heavy metals, and provide the results to the EPA under its licence.

Last year Sydney Water noted an increase in a pesticide in the effluent at Malabar and traced it to a dog-washing business in St Marys, which was putting run-off directly into the sewer.

Sydney Water also monitors the small creatures which live in the sediments around the outfalls. The EPA conducts its own studies of the extent of the plume from the outfalls.

But there have been no fish studies since 1993.

This was despite findings by NSW Fisheries in 1993 that there were significant changes in the types of species found at the outfalls, although there was no decrease in overall fish numbers.null

Professor Patrick Troy, from the Centre for Resource and Environmental Studies at ANU, believes the issue is serious.

"When the sewerage system was first put into Sydney, the sewage flow was pretty benign," Professor Troy says.

"But with increased industrial processes and the stuff we put in ourselves - endocrine drugs, fertility control drugs, cholesterol drugs and depression drugs - there is now a very serious issue about the effects of this cocktail."

Influential on the establishment of the outfalls was a study by the State Pollution Control Commission in the 1980s which revealed alarming mutations in fish caught around the old on-shore sewage outfalls.

The deep ocean outfalls, taking advantage of the East Australian Current, dilute the sewage more quickly. But many professional fishers worry that the plumes, which travel from Malabar, North Head and Bondi as far south as Stanwell Park, may be damaging vital fishing grounds.

Abalone farmers on the South Coast have cited the outfalls as the reason for perkensis, a disease that is devastating their industry.

Meetings between representatives from the industry and the Minister for Fisheries, Ian Macdonald, have discussed declining numbers of abalone.

"We've been trying to get some monitoring done but the Department of Fisheries says it is due to changes in ocean temperatures."

A Department of Fisheries spokeswoman said: "Our responsibility is to check on the condition of life but only in response to concerns raised by the Environment Protection Authority."

Algal blooms, known as red tides, off Sydney last year have also been blamed on the outfalls.

However, scientists are divided over whether they were due to the added nutrients from the outfalls or natural upwellings of the current, which cause small organisms to flourish.

Sewage pollution in estuaries has long been recognised as a threat to oysters. But more recent research in Britain has warned that a common industrial chemical - nonylphenol - is causing oysters to turn into hermaphrodites.

The chemical was found to cause damage at very low levels.

The EPA has flagged that it will focus on the possible effects of cocktails of chemicals.

But at the moment it insists that sediment monitoring, which looks at tiny creatures called benthos, has not uncovered any adverse results.

"The benthic communities around the outfalls remain very diverse and highly variable. No catastrophic decline [or increase] has been observed in any of the benthic families," the EPA said in statement.

Benthos collected at Malabar in 2003 are similarly diverse and as abundant as previous years.